Telephone-exchange system.



C. L. GOODRUM. TELEPHONE EXCHANGE SYSTE VI. APPLICATION FILED SEPT. n,1914.

Patented Apr. 3.1917.

In van; for".- 04 wr/es L. oodrarn.

UNITED STATES PATENT-Q OFFICE.

CHARLES L. GOODRUM, OF BZlEtOQKlTYN, NEW YORK, ASSIGNOR T0 WESTERNELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPIZ'BATION OFNEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters Patent.

Patented Apr. 3, 1917.

Application tiled September 11, 1916. Serial No. 119,510.

ts object is to provide a circuit arrangement for systems of thischaracter wherein a selector, failing to llnd an idle trunk, will beautomatically restored to the beginning of the selected trunk group andagain driven actisuch trunk group, this operation continuing until anidle trunk is found.

To accomplish this result the selector, in

the present embodiment of the invention, is provided with a release.magnet in addition to the regular release magnet which will draws bothholding pawls. This additional release magnet will withdraw the secondarpawl only, whereupon the brush shaft is restored in So for as itssecondary movement isconcerned, being retained in its set primaryposition in operative relation to the selected trunk group by theprimary holding pawl. The secondary motor magnet then is operated todrive the selector hrushes ovelj such trunk group again.

The invention will be more readily understood when described withreference to the no inpanyin drawing, which shows only so much of atelephone exchange system as is necessary to a comprehension of theinventiont" l The invent-ion will be best understood frorn ax detaileddescription of the operation. U on the removal of the receiver atsuhstallion A, a. line-tinder l the brushes 7;, b", and torminalls t, t,only of which are. shown, is set in motion to lind the calling,' line.\Vlieii the calling, line has been extended to a first selector FS, thestepping relay 1 thereof is energized over the following circuit: freepole of battery, right winding of relay 'l, arm 2 of the first selectorside switch and its first Contact, conductor 3, brush ,0,

multiple t, line conductor 4, through the tele at substation A, lineconbrush 1), conductor. 6, lirst contact, lei't phonic apparatus duetdi5, multiple t, snle+switch arm 7 am] its winding of relay, 1, to ground.Relay 1 in 'teshterminals are grounded.

attracting its armature, energizes a slow relay 8, which in a ttraetingits armature inter poses a break in the circuits of release magnet RMand pr3pnres a circuit for a slow relay 9, which controls the escapementmagnet 10 and also connects the primarv magnet PM to the hack contactoft-he stepping relay l.

'lhe calling p: rty now operates his sender h to transmit the lust digitof the wanted numla'r. The sender S is of the well-known type, which inreturning to normal interrupts the line ri and a number of timescorresponding to the digit in question Upon each retra tion oflhe'arniature of relay 1 an impulse is tr; nsuiiticd over the followingpath to primary magnet P: ground, arma ture and lJlltli contact of relayl. armature and l'ront contact of rcla S, which being slow holds its a1mature attracted though its circuit is interrupted, 'comluctors 133' andll. secondary Ulldltlllltll conta t- HUX, magnet PM. 'l'rce pole ofbattery. The slow relay is'cncrgizcd in parnllcl with magnet lhliandremains energizrd during the transmission of the impulses. l'hi'-".-..rela in attracting! its armature energizes escape magnet 10 Thearmature ol' matrnet l.\l is prorided with a stepping pawl 37, whichengages a rotary ratchet 3 5 on the hrush shalt J1, and. rotates theshaft to position a set of brushes 11 in operative relation to thedesired trunk group.

When the sen ler S restores and mainlains the line circuit closed, slowrelay t alter a slight'interral ,liwomcs dei nergimal, open ing thecirruit of escape magnet 10, uhich thereupon pass:s the side switch toposi tion Ll. i i

In position :2 "he following circuit is closed for the secondary magnetSM todrive the positioned set olbrushes orer the selected trunli group:lrcc pole of hatter), contact if) ol release magnet R'M', magnet HM andits armature an I hack contact, conductor lo, side switch arnrlT and itssecond contact, to ground at the armature and front contact ot relay 1.'lhe'armature ot' magnet SM is provided with a stepping pawl :54, whichengages a vertical rat het 2! to elevate the shaft ll. ln liosition lot:the side switch, arm 18 connectn the escape magnet 10 in oil'- cuit.with the tgst hrushof thc set ol p tinned:brushes. idle trunks are thosewhr 'lhc escape reached. Therefore, when the first idle magnet isconstructed to release the side switch from position 2 to position 3upon its energization, when the hrst idle trunk is stepping relay'lfromthe connecting circuit conductors 3 and. 6, and extend 'the'callingline throu h to the talking brushes of the selector; %n this osition,side-switch arm connects the re ease magnet to the third or release wireto prepare the release .circuit which 1 is closed uponthedisestablishment of the connection. The vertical ratchet22 is'normallyengaged by a hold ng pawl '24 and the rotary ratchet by a holdingpawl-25. The awl 24 is integral with the armature 26 o the releasemagnet RM-, whicharrnature'is pivotedon a *pin27. Thepawl is integralwith the armature 2813f the release magnet RM, which armature is alsopivoted upon pin 27.

Upon the replacement of the receivers, a ground isplaced upon test wire19'leading from the, connector, and closes the circuit of release magnetRM,.this circuit'including a primary off-normal contact PON closed uponthe first rotary step of the shaft 21. This magnet in attracting itsarmature 28, withdraws the rotary pawl 25, and the arm 29 of sucharmature acts through'arm 30 on the armature 26 to withdraw the verticalpawl 24. The release magnetwhen energized, locks itself over contact 31and remains locked up until the brush shaft 21 restores and opensoif-normal'con'tact PON.

.the brushes over theentire group, and "after "If, however, during thehunting 'opera tion oftherselector its movement s not stopped, thesecondary magnet SM drives the "brushes have cleared the last set oftrunk terminals, an insulated projection 32 on the brush-shaft 21 closesa contact 33 andenergiz es release magnet RM. 'This I magnet in'attractingits armature 26, withdraws the vertical pawl 24: from thevertical ratchet 22 but does not disturb the rotary pawl 25,The-armature 26 in its attractive movement opens contact 15 and, closescontact'33"v .The opening of the former contact prevents furtheroperation oithesecondary Y magnet-SM, and,theclosing of-the latter 66contactnlaintainsithe magnet R'M locked I N; yclos'es upon the firstupward step of the ,over a circuit includinga contact 35, which brushshaft 21. .The withdrawal of pawl 24 causes the, shaft 21 to .dropnandwhen it :reachesits lowermost position, the projec tlon 32zopenscmitact. 35, unlocking magnet The release circuit for the selectorin this caseis as followszfree pole of battery, re.- lease magnet RM,contact PON, arm 20 and its second contact, armatures and back contactsof relays 8 and 1 to ground.

\Vhat is claimed is:

1. In a telephone exchange system, in I combination with telephonelines, a selector, means for associating calling lines with saidselector, trunk groups terminating in said selector, primaryand-secondary driving magnets for said selector, means for operatingsaid primary magnet to set said.

selector in operative relation to' a trunk.

group, automatic means for thereupon-operating said secondary magnet todrive the selector o er said group, means for stopping the*selectoronthe first idle trnnky-and means operated if 'no idle trunk ispresent for restoring said selector in operative relation'to said trunkgroup andjfor "again driving the same thereover.

2. In a telephone exchange system, in combination with telephone lines,a selector, a brush shaft therefor, means for associating a calling linewith said selector, primary and secondary stepping magnets for saidselector, primary and secondary ho1d-' in-g pawls for said brushshaft,arelease magnet adapted to withdraw both pawls,

an auxiliary release magnet adapted to withdraw only the secondary pawl,trunk groups terminating in said selector, a. sender for operating saidprimary magnet .to set said selector in operative relation to a. trunk.group, automatic means forthereupon opera ating saidsecondarv magnet todrive the Q selector thereover, means operatijye on thedises'tablishm'ent of the connection ito operate said release magnet torestore the brush shaft, means operated if the selector -fails to iary'Ina' .etto withdraw the secondary 'findf'an idle trunklfor'operating'said auxil- I pawl, an means for thereupon again open-7f, ating thesecondary magnet to drive the selector over the selected trunk group.

3. In a telephone exchange system, the

combination with telephone lines, a 'selec tor, trunk groups terminatingtherein, ,pri-

.mary and secondary stepping magnets for said selector, a drivingcircuit-for said sec} ondary magnet, primary and secondary holdingpaw-ls for said selector, a release magnet adapted to withdraw bothvpawls and an auxiliaryrelease magnetadapted to w thdraw onlythesecondary pawl, a sender for operating said pr mary magnet to 18 theselector in operative relation to a' annies trunk group, means forthereupon closing"- said driving circuit to step the selector moreover,a testinq magnet adapted to be operated upon the finding of the idletrunk to open the circuit of said secondary magnet,- means actuated whenthe selector m reaches the end of the trunk group'for oper- 4 ating theauxiliary release magnet, a 105:]:-

3g circuit. therefor, said magnet being apted to withdraw theseoondaryflpawl, to

' open the circuit of the eeoondary'magnet and to close said locking chunit, and means for reclosin opening sa1 said driving circuit and in:

looking CiICllllL when the selector is restored to operative relation tothe 1 said trunk group to drive t'. 1e brushes again overisaid groun. I

' In witness whereof, I hereunto subscribe llngqename this 8th day ofSeptember A. D-.,'

CHARLES L GOODRUM.

